The present invention relates generally to the field of plastic pipe fittings, and more particularly, is directed to an improved pipe fitting construction system including integral locking and sealing features.
In piping systems in general and in plastic piping systems in particular, it is the usual practice to provide lengths of pipe in suitable increments, such as ten feet or twenty feet, for use in constructing a pipe line of a desired size. Each pipe length is fabricated to the designed internal diameter, usually by the extrusion process, and then has its ends worked as necessary to provide one bell or hub end and one spigot end of predetermined interrelating design to allow adjacent lengths of pipe to be joined in a secure and leak proof manner.
Usual fittings such as tees and wyes are employed where design criteria require, and such fittings form the subject matter of the present invention. Fittings of smaller sizes are generally molded or are otherwise formed for use with pipe sections of equal diameter. In the case of larger diameter work, the molding process cannot normally be economically employed and accordingly it is common practice to fabricate large diameter fittings of separate molded or extruded plastic components and then to join the separate parts together. For example when fabricating a wye fitting of twelve inch diameter, the center part in the configuration of the wye shape was first formed. Each of the three wye ends was then equipped with a bell or hub of suitable configuration to receive and seal against the spigot end of an interconnecting length of plastic pipe. In order to generate sufficient strength in each hub connection and to assure a leak proof fitting, a solvent weld or chemical junction was first formed between a hub and one free end of the wye center body. After all of the hubs were solvent welded in place, a second plastic weld or peripheral heat junction was then applied at each connected hub. These operations have proved to be time consuming, costly and subject to frequent quality control rejections. The fitting construction of the present invention seeks to overcome all of the problems incident to the present pipe fitting construction techniques. As used herein, the term "large diameter" is defined to mean pipe sizes twelve inches in diameter and larger.